Inhibition of NF-κB pathway in LPS-stimulated THP-1 monocytes and COX-2 activity in vitro by berry pomace extracts from five Vaccinium species

Abstract

BACKGROUND: Berry processing residues called pomaces are rich in polyphenols, sugars, organic acids, and minerals. Polyphenols are reported to reduce the risk of non-communicable diseases, including cardiovascular diseases, cancer, and diabetes mellitus, owing to their anti-inflammatory activity. OBJECTIVE: We aimed to assess the anti-inflammatory properties of five Vaccinium spp. berry pomace extracts using LPS-stimulated THP-1 monocytes and a COX-2 inhibition assay. METHODS: THP-1 monocytes were pre-incubated with chemically characterized bilberry, blueberry, American cranberry, bog cranberry, and lingonberry pomace extracts following LPS stimulation. NF-κB nuclear translocation was assessed by flow cytometry. TNF-α, MMP-9, IL-23, IL-10, IL-1β, CCL22, and IL-8 secretion was analyzed in cell culture supernatant by using Luminex assay and ELISA. The expression of IL-6, TNF-α, IL-10, IL-23, and TGF-β1 was assessed by qPCR, and COX-2 activity was determined by a fluorometric inhibition assay. RESULTS: All berry pomace extracts tested, except for lingonberry, inhibited LPS-induced NF-κB nuclear translocation. All five extracts significantly downregulated the expression of pro-inflammatory cytokines and inhibited COX-2 activity in vitro. CONCLUSIONS: Vaccinium spp. pomace extracts demonstrated anti-inflammatory properties in an LPS-stimulated THP-1 cell inflammation model and inhibited COX-2 activity. Thus, Vaccinium spp. berry pomace extracts could serve as a valuable source of anti-inflammatory compounds.